title: A nanoparticle-based sensor for visual detection of multiple mutations.
abstract: Disposable dipstick-type DNA biosensors in the form of lateral flow strips are particularly useful for genotyping in a small laboratory or for field testing due to their simplicity, low cost and portability. Their unique advantage is that they enable visual detection in minutes without the use of instruments. In addition, the dry-reagent format minimizes the pipetting, incubation and washing steps. In this work, we significantly enhance the multiplexing capabilities of lateral flow strip biosensors without compromising their simplicity. Multiplex genotyping is carried out by polymerase chain reaction (PCR) followed by a single primer extension reaction for all target alleles, in which a primer is extended and biotin is incorporated only if it is perfectly complementary to the target. Multiallele detection is achieved by multiple test spots on the membrane of the sensor, each comprising a suspension of polystyrene microspheres functionalized with capture probes. The products of the primer extension reaction hybridize, through specific sequence tags, to the capture probes and are visualized by using antibiotin-conjugated gold nanoparticles. This design enables accommodation of multiple spots in a small area because the microspheres are trapped in the fibres of the membrane and remain fixed in site without any diffusion. Furthermore, the detectability is improved because the hybrids are exposed on the surface of the trapped microspheres rather than inside the pores of the membrane. We demonstrate the specificity and performance of the biosensor for multiallele genotyping.
authors.affiliation: Department of Chemistry, University of Athens, Athens 15771, Greece.
authors.forename: Dimitrios S
authors.initials: DS
authors.lastname: Elenis
authors.forename: Penelope C
authors.initials: PC
authors.lastname: Ioannou
authors.forename: Theodore K
authors.initials: TK
authors.lastname: Christopoulos
mesh_terms: D000327:Adsorption; D000906:Antibodies / Q000737:chemistry / Q000276:immunology; D015374:Biosensing Techniques / Q000379:methods*; D001710:Biotin / Q000737:chemistry / Q000276:immunology; D004247:DNA / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification; D004252:DNA Mutational Analysis / Q000379:methods*; D017931:DNA Primers / Q000737:chemistry / Q000235:genetics; D015342:DNA Probes / Q000737:chemistry / Q000235:genetics; D005838:Genotype; D006046:Gold / Q000737:chemistry; D053768:Metal Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D008855:Microscopy, Electron, Scanning; D008863:Microspheres; D009693:Nucleic Acid Hybridization; D016133:Polymerase Chain Reaction; D020641:Polymorphism, Single Nucleotide / Q000235:genetics; D011934:Reagent Strips / Q000737:chemistry*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D000906:Antibodies; D017931:DNA Primers; D015342:DNA Probes; D011934:Reagent Strips; D001710:Biotin; D006046:Gold; D004247:DNA